Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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237
FXUS62 KRAH 060014
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
814 PM EDT Wed Jun 5 2024

.SYNOPSIS...
A series of mid-level disturbances will move east and interact with
an unseasonably moist airmass over NC through Thursday. A pre-
frontal trough and cold front will move across the area Thursday
evening through early Friday. High pressure will move in with fair
weather for the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Wednesday...

As surface high pressure off the Mid-Atlantic coast continues to
pump warm moist air into the region from the south, with showers and
storms continuing to develop over the next few hours. Best chance
for storms this afternoon will be along and east of US1. This is
also the area where WPC has a marginal risk for flash flooding.
While coverage will once again be isolated this afternoon and
evening PoPs remain at around 30-45% chance for areas until at least
midnight. After midnight atmosphere should destabilize and a few
showers could still be possible with the upper distance moving
overhead. Clouds are expected to stick around through the morning
before clearing out after sunrise. Lows are expected to be above
average with temps ranging from upper 60s to low 70s.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 230 PM Wednesday...

...There is a Level-1/Marginal Risk For Severe Storms mainly along
and north of HWY 64...

Central NC will lie along the southern fringes of a mature mid-
latitude cyclone that will traverse along southern Ontario and the
Upper Great Lakes. Meanwhile, the associated belt of enhanced
westerlies will dip down into the Ohio Valley and northern mid-
Atlantic states with the trailing surface front crossing the area
Thursday night.

The day should start start out mostly dry with a near repeat
performance of gradual lifting of the overnight/morning stratus
layer through the late morning/midday.

Thereafter, a loosely organized line of showers and storms, likely
focused along the H8 trough/front, will move east off the mtns and
foothills and into the western Piedmont between 18-21z. The
convection is expected to move east through the remainder of the
afternoon and evening hours, before exiting the eastern/coastal
plain counties ~03z. It is unclear how the line will evolve as it
moves eastward. However, there is a increasing signal in the latest
hi-res model guidance that the line could weaken significantly after
sunset, especially across the southern and southeastern portions of
the forecast area.

Deep layer shear over NC has also trended weaker in recent runs,
with some of the guidance indicating a slight increase to 25-30 kts,
in a narrow belt extending along the NC-VA late towards sunset. If
there is chance for any isolated strong to severe storm, it will
likely be across the northern tier counties between 4-8 pm. Damaging
wind gusts are the primary threat.

Highs will be warmer than today, especially across the eastern half
of the forecast area where the later arrival of showers and storms
should allow for some strong heating. Highs ranging from mid 80s NW
to lower 90s SE.

Some isolated showers will be possible overnight/predawn hours
Friday morning as the lagging cold front crosses the area. Lows 65-
70.
&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 200 PM Wednesday...

Friday and Saturday: Aloft, an upper low will meander slowly
eastward through southern Ontario/southern Quebec, Canada Fri and
Sat. The attendant trough will progress eastward through the East
Coast states Fri as a s/w passes over central NC within the trough.
The trough will continue offshore Fri night. Nearly zonal flow
should prevail Sat/Sat night, with a weak s/w or two passing
overhead. At the surface, the cold front should be through central
NC Fri morning and continue eastward offshore through the aft/eve.
Cool high pressure centered just west of the southern Appalachians
will ridge eastward into the area Fri night. A trough may develop
over the area Sat and amplify Sat night, while the high weakens. For
now the forecast remains dry. Highs Fri ranging from low/mid 80s NW
to mid/upper 80s SE, with lows ranging from mid 50s north to mid 60s
south. Temps should be similar Sat/Sat night, highs a degree or two
lower and lows a couple/few degrees higher in some spots.

Sunday onward: There is still some uncertainty in this part of the
forecast, so confidence is on the low side. Aloft, as the parent low
swings through Quebec, Canada and the Northeast US a potent s/w will
drop south out of central Canada, through the northern Plains/upper
MS Valley Sat night/Sun, then continue around the parent low through
the Great Lakes/OH Valley Sun, amplifying the attendant trough in
the process. As the low lifts northward Sun night/Mon, the trough
should swing eastward into (GFS)/toward (ECMWF) the mid-Atlantic.
The s/w should move through central NC Mon night or Tue/Tue night.
At the surface, with the trough over central NC, a warm front may
briefly lift through the area Sun aft/eve, before another cold front
pushes through the area Sun eve/night. The front should stay east of
the area, with high pressure over the Plains/MS Valley through Mon
night. Beyond that, the medium-range guidance varies greatly, with
the ECMWF showing a low tracking along the Southeast US/Carolina
coast Mon night and Tue, while the GFS slowly develops a westward
retreating, inverted coastal trough Tue/Wed. The best chances for
showers/storms will largely be tied to the initial s/w sometime
between Sun eve and Mon night. Additional showers/storms will be
possible through mid-week, but confidence is low at this time.
Temperatures should be within a category or two of normal.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 810 PM Wednesday...

24-hour TAF period: The broken band of showers over the northern and
western Piedmont will continue to weaken as it pushes east this
evening, with no significant aviation impacts expected. Just mid and
high clouds will stream across central NC, before IFR/MVFR low
stratus again develops late tonight by around 08-10z. The highest
confidence of this occurring is at the Triad terminals (INT and
GSO), followed by RDU and FAY, and lastly RWI. S/SW winds should
stay elevated overnight (around 5-10 kts) and this combined with the
low stratus mean fog is not expected to be a concern. Conditions
will improve to VFR by mid to late morning, but a line of showers
and storms associated with a cold front is expected to move east
through central NC during the afternoon and evening. The best guess
is for the line to reach the Triad terminals by mid afternoon,
followed by RDU near the end of the TAF period, though timing is
still a bit uncertain. MVFR or even IFR ceilings and visibilities
will be possible as the line moves through, along with gusty winds.

Outlook: The line of showers and storms will continue to impact
southern and eastern parts of the area through the evening, with
sub-VFR conditions still possible. VFR conditions and dry weather
are expected to return Friday through the weekend before another
cold front and upper disturbance bring more shower and storm chances
late Sunday into Monday.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...CA/MWS
NEAR TERM...CA
SHORT TERM...CBL
LONG TERM...KC
AVIATION...Danco